Convert the following to 24-hour clock time:

For a.m. times (except 12 a.m.), the hour remains the same.

$$5:06 \text{ a.m.} = \boxed{\text{05:06}}$$

For p.m. times (except 12 p.m.), add 12 to the hour.

$$4 + 12 = 16$$ $$4:09 \text{ p.m.} = \boxed{\text{16:09}}$$

12 a.m. is the start of the day in 24-hour format, which is 00:00.

$$12:40 \text{ a.m.} = \boxed{\text{00:40}}$$

For p.m. times (except 12 p.m.), add 12 to the hour.

$$3 + 12 = 15$$ $$3:44 \text{ p.m.} = \boxed{\text{15:44}}$$

For a.m. times (except 12 a.m.), the hour remains the same.

$$4:59 \text{ a.m.} = \boxed{\text{04:59}}$$

For p.m. times (except 12 p.m.), add 12 to the hour.

$$4 + 12 = 16$$ $$4:19 \text{ p.m.} = \boxed{\text{16:19}}$$